The overall object of this study is to determine how the growing tumor influences the lipid metabolism of the host. The investigation will be carried out in several directions simultaneously: I. The nature and mechanism of action of a lipid mobilization factor (LMF) previously found in the blood of tumor-bearing mice and human cancer patients, in extracts of tumor tissue and in culture medium from growing tumor cells, will be investigated. Sources for isolation and purification of LMF in amounts suitable for characterization will be sought. In particular, serum-free medium from growth of SL12 cells will be investigated as a ready source. II. The action of LMF on an animal host (AKR mice) will be investigated from the points of view of a) generality of types of tumors and animal hosts, b) appearance in relationship to tumor growth and c) formation and action of antibodies to LMF protein. III. The occurrence of LMF in human cancer patients will be documented from the points of view of a) earliest appearance, b) generality for types of tumor, c) other disease states and d) changes in LMF in patient blood in response to standard therapy procedures. IV. The effect of a growing tumor on fatty acid oxidation by the host liver mitochondrial system, whether mediated by LMF or some other mechanism, will be investigated. The defect in Beta-oxidation of palmitate in tumor-bearing mice will be characterized and the nature of a Beta-oxidation defect in certain controls, possibly in a precancerous state, will be clarifed.